The present invention relates generally to semiconductor devices and semiconductor device packaging and, more particularly, to semiconductor device packages with electromagnetic interference shielding.
Semiconductor device packages or integrated circuit chip carriers are used in many high-density electronics applications. The integrated circuits or semiconductor devices are protected from the external environment by encapsulation with an epoxy material or transfer molding a thermoplastic resin about the device. However, as circuits become smaller, denser, and operate at higher frequencies and in harsher environments, there is a growing need to shield the circuits from radiation, such as radio frequency interference (RFI) and electromagnetic interference (EMI). For example, cell phones and other mobile devices need to be protected from such radiation. Automotive circuits, such as microcontrollers that are mounted near the spark plugs also need to be shielded, and the plastic encapsulant does not provide EMI or RFI shielding.
Conventional shielding systems use a conductive metallic enclosure that surrounds the circuit to be shielded. The enclosure protects the internal circuit from EMI and RFI and prevents the escape of RFI or EMI signals generated by the circuit. Another solution is to place a metal cap over a semiconductor device either before or after molding the package. This solution is applicable to ball grid array (BGA) packages that have a large semiconductor die (i.e., at least one inch squared). Yet another solution is to provide a metal coating over the encapsulated device. However, all of these solutions have some drawbacks. For instance, using a conductive metal enclosure adds to the overall size of the package and requires an additional soldering step to attach the metal shield to the device, with the heat generated by the additional soldering process potentially harming the device.
Therefore, a need exists for cost-effective, component level shielding that can be used in a variety of packages with any semiconductor die size.